Jacketed optical fiber cable (herein jacketed cable) is well known and comprises an optical fiber adhered to a surrounding tough polymer jacket. Unlike typical buffered cable, the fiber in a jacketed cable is not free to move within its protective covering. Jacketed cable is generally recognized as having superior crush resistance and possibly a broader operating temperature range than other optical fiber cables.
Jacketed cable has been used historically in naval and other military applications. Typically, these cables were connectorized with ST bayonet-type connectors. These are relatively old-style connectors having a large form factor and a screw-type connection mechanism. In the ordinary course of retrofitting this equipment, it would be desirable to replace these old fashioned connectors with more modern small form factor connectors such as the LC and MU connectors. Although it is desirable to change the connector interface, it is undesirable to run entirely new fiber throughout the vessel.
Furthermore, applicants have discovered that connectors, particularly small form factor connectors, are susceptible to torsional rotation of the cable relative to the housing. Specifically, because there is no “give” between the jacket and the fiber within the jacket, any torsional motion on the jacket will necessarily create a torsion force on the ferrule assembly. If this torsional force is high enough, it can cause the connector housing to deform and allow the ferrule assembly to rotate within. This rotation diminishes the quality of optical interface and may even damage the connector if the rotation is severe. Therefore, preventing the ferrule assembly from rotating within the housing is critical in the use of a tight jacketed fiber cable.
Applicants have found that small form factor connectors are far more susceptible to this torsional rotation than their larger predecessors. Without being bound to any theory for this susceptibility, applicants believe that the small radius connectors lack the torsional rigidity of their larger predecessors. For example, a typical LC connector comprises a housing defining an octagonal cavity and a ferrule assembly having an octagonal outer geometry which fits into the cavity. The corners of the octagonal interconnection, however, are insufficient to resist the rotational forces common on jacketed cables.
Thus, there is a need for a small form factor optical connector that can be terminated to an existing jacketed optical fiber cable and that is resistant to deformation when a torsional force is applied to the cable jacket.